Investigation of in-situ Chemical Reactions of Al_2O_3-SiC-SiO_2-C Refractory and Its Interactions with Slag

摘要

Experiments were carried out to investigate in-situ reactions of refractory and its interactions with slag (composition: 45.4 percent SiO_2+36.6 percent CaO + 15.9 percent Al_2O_3) using a horizontal furnace by detecting CO and CO_2 contents in off gas with an infrared (IR) analyzer. The composition of refractory is 69.4 percent Al_2O_3+7.3 percent SiO_2 + 10.6 percent SiC + 12.7 percent C. Temperature was from 1773 to 1873 K. The samples after high temperature experiments were analyzed using X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM)-Energy Dispersive Spectrometer (EDS). Mullite was detected after refractory samples were maintained at high temperatures. The refractory/slag reaction was evaluated by calculating the carbon removed. Carbon removal process was a two-step reaction, in the beginning the carbon was removed very quickly (fast reaction stage) and both CO and CO_2 gases were detected by IR analyzer. Then after around 2000 s the reaction slowed down and no CO_2 gas could be detected (slow reaction stage). The main in-situ reaction product was SiC rather than SiO. Slag showed good wetting with the refractory and penetrated into it through pores. Low melting point compounds, anorthite (CaAl_2Si_2O_8) and gehlenite (Ca_2Al_2SiO_7) were detected after heating refractory for 7200 s while remaining in contact with slag.